Specimen:

SPECIMEN DETAILS:

Organ: Ureter
Origin: Monkey
Staining: Haematoxylin Eosin (H&E)

METHOD AND SPECIMEN DESCRIPTION:

Normal histological section of the ureter, stained with an overview stain. For a more detailed description of the ureter’s histological features, please refer to Section 12.6

OBJECTIVE OF THE EXAMINATION:

To understand the histological structure of the ureter, with attention to its specific epithelial and muscular features.

Special Features of the Specimen:

In general, the ureter is a muscular tube that, in its empty or contracted state, exhibits a star-shaped lumen due to the longitudinal folds of its mucosa, which is lined by transitional epithelium (urothelium).

The wall of the ureter, as in other parts of the urinary outflow tract, is divided into three principal layers:

• Tunica mucosa
• Tunica muscularis
• Tunica adventitia

The urothelium consists of several cell layers. Its superficial covering cells (also called umbrella cells) are often multinucleated and can expand their apical membrane by incorporating subapical discoid vesicles, allowing the lumen to stretch during urine transport. These cells also possess uroplakin plaques in their apical membrane, which provide enhanced chemical and mechanical resistance to urine.

Beneath the urothelium lies the lamina propria, composed of loose connective tissue rich in elastic fibers and blood vessels, forming part of the mucosal layer.

Below this, the tunica muscularis is composed of smooth muscle bundles arranged spirally and separated by connective tissue septa.

• In the proximal ureter, the muscularis consists of two layers (inner longitudinal and outer circular).
• In the distal ureter, a third outer longitudinal layer is added.

Externally, the tunica adventitia consists of connective tissue containing blood vessels and nerves, which anchor the ureter to surrounding structures.

TASKS:

• Identify the tunica mucosa, tunica muscularis, and tunica adventitia.
• Observe the urothelium with its superficial covering (umbrella) cells.
• Note the star-shaped lumen of the ureter in its contracted state.
• Examine the arrangement of smooth muscle fibres within the muscularis.

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